Months had passed since I had seen my dear friend Holmes. After the curious case of A Scandal in Bohemia, Holmes and I drifted apart, I devoting time to my marriage and civil practice, and he to his solitary genius. Yet one night—the first of November, 2009 as I recall—I felt a sudden and incomprehensible urge to see my companion. My stride led me instinctually to Baker Street, where I found Holmes reclining in his armchair, deep in an opium stupor. His droopy-eyed contentment told me everything: He had just solved a case.

“Watson,” he said casually. “What do you make of these items?” He stood unsteadily and bent over a large trunk, from which he extracted a number of items: a thermometer, a stethoscope, a mosquito net, and a ticket stub for the Yale Peabody Museum.

I was stunned. “Why nothing, my dear Holmes! What could connect such a disparate collection?”

“A case,” he replied. “They are all clues from my wildest and most challenging mystery yet. I call it: The Case of the Unwanted Visitor.”

I had always been quite baffled by the cases that Holmes dismissed offhand, and for him to refer to a case as “challenging” was quite singular. I settled down into an armchair to listen, confident that this tale would make my best story yet…

A FORTNIGHT BEFORE ON A RAINY AFTERNOON IN New Haven, Conn., Holmes was wandering the streets, believing that America’s cities teemed with unsolved crimes. He was correct; about a half-mile up Whitney away from Yale University’s campus, the newest exhibit at the Peabody Museum cried out for Holmes’ expertise. He entered the exhibit entitled “Disease Detectives” and was greeted by Yolanda, the statue of a beautiful African woman with closely cropped hair and a distinct yellowing of the whites of her eyes. She was desperately in need of help, but her feminine reticence and the general inability for statues to speak rendered her silent. Her story, however, was displayed prominently on the adjacent wall under the title: The Case of the Unwanted Visitor. Using his top-notch literacy skills, Holmes read the museum display and deduced that Yolanda was a young woman from West Africa who had been living in the United States for the last 10 years. On a trip home to visit her family, she had fallen ill suddenly and was taken to the village clinic. No one else in her family was stricken.

It was a curious case indeed. Yet, before Holmes could progress to the next stage of the exhibit, he caught a glimpse of the most unbelievable sight out of the corner of his eye: dinosaur skulls! Three Ceratopsian skulls, to be precise, for Holmes is always scrupulous in indentifying the correct genealogy of the many fossils he comes across in his line of work. What could be the explanation for these skulls so close to the Disease Detectives exhibit? Were they somehow related to Yolanda’s mysterious illness?

Holmes followed the skulls to the left and into the Great Hall. He was immediately greeted by the gigantic skeleton, which he estimated to be approximately 70-90 feet long. He identified the dinosaur as Brontosaurus, a plant-eater despite having teeth “like a garden rake.” Holmes was very excited by this discovery for he knew immediately that this skeleton was the only one of a true Brontosaurus.

The wealth of Holmes’ knowledge reminded him that in 1877, Yale professor O.C. Marsh discovered a dinosaur skeleton and named both the skeleton and the species Apatosaurus. Two years later, when the professor encountered a similar skeleton with a different number of sacral vertebrae, he assumed it was a separate species and named this species and this skeleton, the very same one standing in the Great Hall, Brontosaurus.

Yet his assumption was inaccurate; these fossils were simply from an older Apotosaurus with more sacral vertebrae. The Brontosaurus species disappeared, yet this particular skeleton retained its name: “Brontosaurus.” After Holmes’ amazement abetted, he returned to the question at hand: What about these three Ceratopsian skulls? A quick glance around the Great Hall explained the problem immediately: The Age of Reptiles mural was missing—Holmes deduced it was being cleaned—and the skulls had been relocated during the process.

This red herring dismissed, Holmes returned to Yolanda, visiting her in the panorama of the West African clinic that was located mere steps from the Jurassic-Age Great Hall. She sat in a chair in the corner of the clinic, staring stonily ahead. He felt her head—it was too warm. Using the tools at hand, Holmes took her temperature: 101.6 degrees! He also used a stethoscope to hear her heart rate, and was unnerved when he could hear no pulse.

“No matter,” Holmes cried aloud. “I will not be deterred by a second red herring. I know this woman is alive. The stethoscope must be faulty.” He deduced that her symptoms of chills, fatigue, bouts of fever, and yellowing of the eyes were a result of a parasitic infection. But which one?

To narrow down the options, Holmes proceeded to the Lab, where he could look at Yolanda’s blood underneath a microscope and perform a Rapid Diagnostic Test (RDT). At first the blood only looked like an out-of-focus shot of the rose petals from American Beauty, but quickly Holmes noticed something curious.

“Aha!” he exclaimed, noticing the purple Malaria parasites—ring-shaped inside the blood cells and banana-shaped outside.

Holmes’ outburst attracted the attention of two recently arrived detectives: a mother and her young son who wore Spiderman rain boots. They were trying to solve The Case of the Lyme Disease, but that one was elementary detective work, far below the capacities of the great Holmes.

Unfazed by the intruders, Holmes employed the Rapid Diagnostic Test, which confirmed his diagnosis of malaria, probably caused by a mosquito bite because her family’s home didn’t have netting over their beds.

“SO A MOSQUITO WAS THE CULPRIT THAT CAUSED her symptoms?” I asked when Holmes had finished telling me his marvelous tale.

“Culprit? No, Watson,” Holmes explained.

“A mosquito is the vector that transmits plasmodia parasites. The parasites caused the fever, yellow eyes, chills. But now this pretty lady will be back to full health because we caught the disease early.”

“And why did her family not fall ill?” I asked.

“Yolanda lost her immunity to malaria while living in that god-forsaken country of America,” Watson replied.

“But how did you imagine she had such an obscure disease?” I ask, still incredulous.

“Ah, Watson. One child dies from malaria every 30 seconds. That’s 40 school buses full of children dying every day. This disease is far from rare, simply not indigenous to our lovely city of London.”

With those words, Holmes finally fell into an opium sleep. And I, humble man that I am, was glad that Holmes had bestowed his genius onto the Peabody museum, for I learned a great deal from his tale and felt certain that I would visit the museum myself quite shortly, certainly before Sat., Jan. 30, 2010, when the exhibit ends.